v0.2.1: add status messages, fix parallel export progress

- mustAuth: print 'requesting photo library access...' / 'access granted'
- cmdBackupAll: print 'loading photo library tree...' / 'found N albums'
- cmdExport: print 'loading assets...' / 'exporting N assets (mode)...'
- backupTree: print 'album: Name (N assets)' per album
- exportAssetsParallel: slot-based progress shows each asset as it completes
  instead of waiting for all to finish
- Fix data race: use jobs channel instead of shared range iteration

Makefile

@@ -1,6 +1,6 @@
 BINARY     := ./bin/photoscli
 MODULE     := gitea.k3s.k0.nu/tools/photocli
-VERSION    := 0.2.0
+VERSION    := 0.2.1
 BRIDGE_DIR := bridge
 LDFLAGS    := -X main.version=$(VERSION)
 OBJ        := $(BRIDGE_DIR)/photokit_bridge.o